Overload relay



July 27, 1926.

G. B. SCHEER OVERLOAD RELAY Filed April 2 1922 INVENTOR 6 0W 5. \Td'hw ATTORNEY- WITNESSES:

Patented July 27, 1926.

UNITED sures PATENT OFFlCE.

GEORGE B. SCI IEER. OF BERKELEY. CALIFORNIA. APESIGNOR TO \VESTINGHOTJ'SE ELEC- TRIC & MANUFACTURING CGIIIPA'NY,

A CORPORATIGN OF PENNSYLVANIA.

ovERLoAD RELAY.

Application filed. April 29, 1922.

My invention relates to systems of distribution and it has particular relation to circui oontrolling devices such as are em ployed in systems of motor control.

One object of my invention is to provide an operating magnet for an overload relay device Which shall be compact and simple in structure and convenient to assemble.

Other objects of my invention will become apparent from the following description and the appended claims.

In order that an overload relay may be sufficiently sensitive andresponsive in op eration, in addition to the matter of economy, it is desirable that the relay structure be comparatively small. It is preferable, however, to arrange the operating magnet so that the total load current in the system of distribution may traverse the relay. In order to accomplish the latter requirement,it is necessary to provide a winding of symmetrical design wherein the magnetic field circuit is suitably distributed about the operating plunger of the relay to insure balanced freedom of movement of the plunger by eliminating undue frictional losses.

When extremely high currents are carried by the operating winding, the practice has been resorted to, in some instances, of passing a single conductor adjacent to the 0peratlng plunger of the relay. The field induced about this conductor is then depended upon to actuate the relay plunger in accordance With a predetermined setting of the relay. This method is open to the obdistributed about the relay plunger and usually results in unreliable and erratic oporation.

My invention Will be described in connection with the accompanying drawing, in which- Fig. l is a sectional view of apparatus embodying my invention;

Fig. 2 is a view, in elevation, of the apparatus illustrated in Fig. 1.

I do not claim the details of the overload relay as illustrated and which may be of any suitable design, but my invention is peculiarly adapted for use in connection with relays of the type forming the subject-matter of the application of Charles H. Hodgkins, S ria N 2 2. filed Nowel l l l 1ection that the field is not symmetrically Serial No. 557,483.

and assigned to the Westinghouse Electric & ll lanufacturing Company.

I A suitable operating Winding is illustrated in the drawing as comprising two currentcarrying conductors 1 and 2 Which are arranged symmetrically with respect to the operating plunger 3 of the overload relay 4. The plunger 3 is capable of vertical movement within a shell or tubing 5 of non-magnetic material. The conductors 1 and 2 are suitably disposed and are insulated from the metallic parts of the relay.

The current is fed through the relay conductors 1 ant from bus bars 6 and 7 which may be located on the rear of the control panel or base 8. The conductor 1 is connected, at one end, by means of a bolt 9, to the bus bar 6 and is connected, at its other end, by means of a bolt 11, to the bus bar 7. Similarly, conductor 2 is connected to bus bars 6 and 7 by means of bolts 12 and 13.

The form and dimensions of the conductors 1 and 2 should preferably be such that the conducting bolts 9, 11, 12 and 13 may be located sufiiciently clear from the relay plunger to ensure that the operation of the plunger will not be elfected by the magnetic field surrounding these bolts. It will be understood that, since a large current is necessarily carried by the bolts, a high field flux is induced thereby.

Assuming that the load current of the system is flowing in bus bars 6 and 7, a circuit may extend from bus bar 6 through bolt 9, conductor 1 and bolt 11 to bus bard. Another circuit extends from bus bar 6 through bolt 12, conductor 2 and bolt 13 to bus bar 7. It should be noted that the di vided flow of the current in the circuit, as traced, traverses the relay conductors in op posite directions. The current flows in conductor 1 through the relay from right to left and the. current in conductor 2 flows from left to right. The current in conductor 1, plus the current in conductor 2, is equal to the total current flowing in the bus bars 6 and 7.

From an inspection of Fig. 1, it becomes evident that, since the current is oppositely directed through conductors 1 and 2, the lines of force 1n the magnetic fields surrounding these conductors are in the same direction on adjacent sides thereof. That is to y, a u stantially umf rm d s lbin tion of magnetic force is effective for actuat inc; the plunger 3.

It will also be evident from inspection of the drawing that, without dividing the current into two paths, described, it would be necessary for the total load current to traverse both of the conductors l and 2, arranged in the form of a loop, as is common-- ly done and which requires conductors of approximately twice the size of those em ployed in my. invention. To obtain the ad ditional winding space necessary to accommodate the larger conductors would necessitate the use of a relay of considerably larger size, thus entailii increased expense and other disadvantages.

I claim as my invention:

1. In a system of current distribution, an operating coil for an overload relay com-- prising two conductors in parallel relation for o 3positely directing and equally dividing the total load current.

2. In a system of current distribution, an overload relay. and an operating magnet therefor comprising two strap members for equally dividing the total curr nt in the system and located so as to p'rovic e a symmetrical magnetic field of maximum intensity between said members.

3. In a system of current distribution, an overload relay, and an o eratinp; magnet therefor comprising strap members syn-rmetrically disposed with respect to the relay and providing divided and opposite y directed paths for the total current in the system.

4. In a system of current distribution, a circuit-controlling device, and an operating magnet therefor comprising a core member and current conductors for equally dividing the total load current to provide a substantially uniform field for said core member.

In a system of current distribution. a circuit-control]ing deyi and an operating magnet therefor comprising a core member and current conductors for dividing the total load current of said system to provide a sul'astantially uniform field having lines of force longitudinally traversingsaid core member.

6. An article of manufacture comprising; two S-shaped current conductors oppositely disposed and with their intermediate portions disposed in parallel spaced relation.

'1'. An electromagn'et comprising a core member and two S-shaped conductors oppositely disposed and with their intermediate portions disposed in parallel relation and perpendicr'ilar to the axis of said core member, said axis being midway between said conductors.

An electromagnet comprising a core member and two S-shaped strap conductors oppositely disposed and with their inter mediate portions located in parallel relation and peipei'idicular to the axis of said core member, said axis being disposed midway between said parallel portions, and means for oppositely directing current through said conductors whereupon a substantially uniform distribution of magnetic force is eli'ective for energizingsaid core member.

In testimony whereof, I have hereunto subscribed my name this th day of April GEORGE E. SCHlillCll. 

